Device and method for a protective mask

ABSTRACT

The present invention concerns a device and method for a protective mask comprising means ( 3 ) for detecting that a protective-mask user is breathing through the breathing filter of the protective mask. The invention is characterized in that the means for detecting protective-mask use are arranged to sense the underpressure that arises in the protective mask during inhalation.

TECHNICAL AREA

This invention concerns a device for a protective mask comprising meansto detect that a protective-mask user is breathing through the breathingfilter of the protective mask as per the preamble to claim 1.

The invention also concerns a method for detecting that aprotective-mask user is breathing through the breathing filter of theprotective mask.

STATE OF THE ART

During military exercises, efforts are made to practice situations thatcould arise during actual combat. One of the situations that can ariseis when an area is exposed to gas attack, in which situations it isdecisive that the soldiers wear protective masks.

Simulating systems currently exist that can be used to train soldiers inwhat to do in the event of a gas attack. These simulating systemscomprise a central unit that communicates with software and/or hardwarein soldier-borne vests. During the simulation of a gas attack thecentral unit transmits information concerning the gas attack to thesoftware/hardware in the vests. The soldiers should carry with themprotective masks, which must be donned in the event of a gas attack. Thenormal filter in the protective mask is replaced with a simulatorfilter. The simulator filter detects an inhalation pressure andcommunicates breathing activity to the vest software/hardware via an IRlink. The breathing activity is processed in the software/hardwaretogether with information from the central unit concerning the gasattack in order to determine whether the protective mask has been donnedand the soldier is breathing through the breathing filter within a giventime frame after the gas attack, in which case no actions are taken. Ifthe protective mask has not been donned within the given time frame, thesoftware/hardware determines that the solider has been wounded orkilled.

DESCRIPTION OF THE INVENTION

One object of the present invention is to improve the simulator filterthat is used in protective masks for use in connection with thesimulation of a gas attack.

This has been achieved by means of a device for a protective maskcomprising means to detect that a protective-mask user is breathingthrough the breathing filter of the protective mask, which device ischaracterized in that the means for detecting protective-mask use arearranged so as to sense the underpressure that arises in the protectivemask during inhalation. For example, a pressure difference sensorarranged to measure a pressure difference between the pressure in theprotective mask and the ambient pressure is used to sense theunderpressure. By sensing the pressure difference, it is possible todetermine with a high degree of certainty whether inhalation through theprotective mask is actually taking place. Measuring the differentialpressure as described above affords a number of advantages. First, noaccount needs to be taken of changes in atmospheric pressure which canoccur, e.g. during changes in the weather or in connection with movementbetween locations that are situated at different elevations about sealevel. Furthermore, it is common practice to establish overpressureinside vehicles in order to prevent toxic gases from penetrating. It isvery likely that the protective mask would be used in just suchsituations, both at the elevated pressure and before there has beenenough time to establish the overpressure. Another advantage is that theelectronics do not need to be calibrated as the components age, or inconnection with operation in varying temperatures.

To further increase the possibility of determining whether inhalationthrough the protective mask is occurring, the pressure difference sensoris connected to a processing unit arranged to compare the pressuredifference values with a reference pattern for a breath in order todetermine whether the pattern of the pressure changes agrees with thereference pattern. The reference pattern can be individually adapted andbased on previously measured values.

Additional processing of the data from the pressure difference sensor inthe processing unit further makes it possible to determine how large avolume of air is being inhaled in a selected breath and/or breathingrate. Using information about the volume of air per breath and breathingrate, the proper usage of the protective mask can be practiced so thatinhalation can occur correctly. In addition, the information providesknowledge concerning the physical stress and degree of concentration ofan individual who is using the protective mask. Following analysis ofthe information, an indication of the condition level of theprotective-mask user can also be obtained.

To distribute the information compiled by the processing unit, theprocessing unit is arranged so as to generate status reports containingthe compiled information, and to supply said reports to a transmitterfor transmission by, e.g. radio.

The invention also concerns a method for detecting that aprotective-mask user is breathing through the breathing filter of theprotective mask. The method is characterized in that the underpressurethat arises in the protective mask during inhalation is sensed in orderto detect protective-mask use.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 shows an example of an encapsulation for a simulator filter for aprotective mask.

FIG. 2. shows an example of the structure of the simulator filter inFIG. 1.

FIG. 3 shows a block diagram that illustrates the function of thesimulator filter.

PREFERRED EMBODIMENTS

In FIG. 1, reference number 1 designates an encapsulation for asimulator filter 2 (seen in FIG. 2) for use in a protective mask. Theencapsulation is designed outwardly in the same way as an encapsulationfor the normal breathing filter of the protective mask. Theencapsulation 1 of the simulator filter thus has the same threadedsocket and protective cover as the normal breathing filter. The normalbreathing filter of the protective mask can thus easily be removed andreplaced with the simulator filter when the protective mask is to beused in simulated gas attack exercises.

In FIG. 2, the simulator filter 2 comprises a pressure difference sensor3 that senses the underpressure that arises in the protective maskduring inhalation. The sensor 3 is in pressure communication both withthe volume of air that is present inside the protective mask and theambient air. As a result, the sensor 3 can detect the pressuredifferences that arise inside the protective mask as a function ofinhalation. In the example in the figure, the pressure difference sensor3 is connected via a hose 4 to an air intake 5. The air intake 5functions as an inhalation tube. The air pressure in the air intake 5indicates the air pressure inside the protective mask. The air pressurein the space around the sensor is also measured. The encapsulationcomprises valves for pressure equalization (not shown), whereupon theair pressure at the sensor 3 indicates the ambient pressure.

The expiration air passes via a one-way valve (not shown) mounted on theprotective mask and out into the surroundings. Note that the expirationthus never passes through the simulator filter. The simulator also hasan air resistance in order to emulate a real breathing filter. The airresistance is adjustable by changing the dimensions of the air intakeopening (not shown) realized in the air intake 5 of the simulatorfilter. The simulator filter 2 also comprises a circuit board 6 that isconnected to the sensor 3 and contains electrical circuits, as well as aprocessor and memory circuits, plus a radio transmitter 7; thesecomponents will be described in detail below.

In FIG. 3, the electrical circuits of the circuit board 6 are describedas two mutually physically separated units, a control unit 8 and acalculating unit 9 connected to a memory 10. One skilled in the art willperceive that the function described below, which is achieved with thecontrol unit and calculating unit, could also be achieved by usingentirely different system designs.

In the example illustrated herein, the control unit 8 controls thefunction of the simulator filter 2. In detail, the control unit 8controls the simulator filter 2 between a standby mode, an awake modeand an active mode, in which different modes the simulator filterfunctions according to different principles. In standby mode the controlunit 8 controls the calculating unit 9, which is operatively connectedwith the pressure difference sensor 3, so as to retrieve pressuredifference data from the pressure difference sensor approximately one totwo times per minute, and to compare the input pressure difference datawith a preset value. As long as the preset value is not exceeded, thefilter remains in standby mode. When the preset value is exceeded, thecalculating unit 9 reports this to the control unit 8, whereupon thecontrol unit 8 changes over to working in awake mode.

In awake mode, a check is run to determine that breathing is present. Indetail, the control unit 8 controls the calculating unit 9 so as tocompare the measured values from the pressure difference sensor with thereference values that form a reference pattern for a breath over aselected preset length of time on the order of several seconds, e.g.five to ten seconds. The reference values are either permanently storedin a memory 10 that is connected to the calculating unit 9, or thereference values are modifiable so that they can be adapted for theindividual who is breathing through the simulator filter in the presentinstance. In the modifiable embodiment, a new reference pattern can bebuilt up based on previously measured values. During the comparisonbetween the reference values and the measured values, data are retrievedfrom the pressure sensor at short intervals, e.g. 5-10 times per second.If, in awake mode, the calculating unit 9 determines that no breathinghas been detected, it reports this to the control unit, whereupon thecontrol unit resumes standby mode. If, on the other hand, thecalculating unit 9 in awake mode does determine that breathing has beendetected, then the control unit 8 will supply a status report to theradio transmitter 7, which informs that the protective mask is beingused. In addition, the control unit assumes its active mode.

In active mode, the radio transmitter 7 is supplied at regular intervalswith a new status report indicating that the protective mask is beingused; this occurs e.g. every five to ten seconds. The active mode ismaintained as long as new breaths are detected. If no new breaths aredetected, the calculating unit 9 notifies the control unit 8 of this,whereupon the control 8 resumes standby mode. In active mode, thedetection process functions in the same way as in awake mode, i.e. newdata are input to the calculating unit 9 from the pressure sensor anumber of times per second, and the input data are compared with a fixedor adapted reference pattern.

In an expanded embodiment, the calculating unit 9 is arranged so that,in active mode, it determines how large a volume of air has been inhaledin the selected breaths. For example, each breath can be selected, orevery second, or every third breath. According to this embodiment, theair volume information is incorporated into the status reports that aresupplied to the transmitter. The calculating unit 9 can also be arrangedso as to determine the breathing rate. Using these two parameters, i.e.air volume per breath and breathing rate, it is then possible, via theinformation in the status reports, to determine whether soldiers usingthe protective mask are actually breathing through the protective masks,and thus practicing breathing through the masks in such a way that theyare breathing as correctly and efficiently as possible. Thecharacteristics of the breathing also indicate, e.g. the physical stresslevel and degree of concentration of the soldier. Analysis of theinformation in the status reports can also, after analysis, provide anindication of the condition level of the soldier.

In the example described herein, the transmitter is a radio transmitter.The transmitter could alternatively be of some other type, such as an IRtransmitter.

In one embodiment the transmitter is arranged so that, during anexercise, it will transmit the status reports directly to a central unitthat receives data from all the soldiers participating in the exercise.The transmitter can alternatively be arranged to transmit at a shortrange, characteristically about one meter. In this embodiment thesoldiers wear vests containing communication equipment and electronicsthat receive the status reports transmitted by the transmitter. Thecommunication equipment in the vest can then be arranged to forward thestatus reports to the central unit.

1. A device for a protective mask comprising means for detecting that aprotective-mask user is breathing through the breathing filter of theprotective mask, wherein the means for detecting protective-mask usecomprise a pressure difference sensor arranged to measure a pressuredifference between the pressure in the protective mask and the ambientpressure, and in that a processing unit connected to the pressuredifference sensor is arranged so as to compare the pressure differencevalues with a reference pattern for a breath in order to determinewhether the pattern of the pressure changes agrees with the referencepattern.
 2. A device according to claim 1, wherein the reference patternis individually adapted and based on previously measured values.
 3. Adevice according to claim 1, wherein the processing unit is arranged tocreate a status report that indicates whether the pattern of thepressure changes agrees with the reference pattern, and to supply saidreports to a transmitter.
 4. A device according to claim 1, wherein theprocessing unit is arranged to determine how large a volume of air isbeing inhaled in selected breaths.
 5. A device according to claim 1,wherein the processing unit is arranged to determine a breathing rate.6. A device according to claim 3, wherein the breathing filter of theprotective mask is a simulator filter, and in that the pressuredifference sensor, processing unit and transmitter are incorporated intothe simulator filter.
 7. A method for detecting that a protective-maskuser is breathing through the breathing filter of the protective mask,wherein a pressure difference between the pressure in the protectivemask and the ambient pressure is measured to detect protective-mask use,and in that the pressure difference values are compared with a referencepattern for a breath in order to determine whether the pattern of thepressure difference values agrees with the reference pattern.